A line code is the code used for data transmission of a digital signal over a transmission line. This process of coding is chosen so as to avoid overlap and distortion of signal such as inter-symbol interference
Line coding refers to the process of converting digital data into digital signals. Whenever we transmit data it is in the form of digital signals, so with the help of line coding, we can convert a sequence to bits (or encoding) into a digital signal which then again converted into bits by the receiver (or can be said as decoded by the receiver). For all this to happen we need line coding schemes which could also be able to avoid overlapping and distortion of signals.
Some necessary characteristics of line coding schemes: